In three-dimensional molding methods wherein a powder layer flattened by movement of a squeegee is sintered by a laser light or an electron beam and the periphery is cut, it is already common to employ a method of molding an object to be molded after the support structure below the object has been molded, instead of molding the object from the location of a base plate in a molding chamber, as disclosed in Patent Document 1, for example.
The main reason for first molding a support structure from below the section to be molded is that:
a) when a support structure is not provided below, a complex operation is necessary for removal from the base plate after molding, since the lower side of the object to be molded is adhered to the base plate, and
b) the region of the lower side of the object to be molded that is not in contact with the base plate moves downward by its own weight while pressing the powder layer below it, and this sometimes interferes with formation of a proper lower side.
The support structure may also employ a construction which is one of:
(1) struts lying between the object to be molded and the base plate, or
(2) upper struts, a middle partition plate or a lower supporting member, lying between the object to be molded and the base plate.
Patent Document 1 actually employs a construction similar to (1) above (FIG. 5, claims 1 and 20) and the construction of (2) above (FIG. 8 and claim 21).
It is naturally intended for the support structure to be removed from the object to be molded and the base plate at the stage where molding of the object to be molded has been completed.
In the middle stage and final stage of molding of a support structure, when the squeegee moves while sliding on the powder layer, the squeegee contacts with protruding regions at corners (nooks) with prescribed angles that have formed on the sintered struts of (1) or the upper struts of (2), and those regions interfere with movement of the squeegee and thus often cause accidents in which sliding of the squeegee against the powder layer is hindered.
However, in conventional three-dimensional molding using support structures, no modifications have been made to maximally facilitate removal of the support structure or to minimize accidents caused by contact described above.
In fact, this technical problem is not at all considered even in Patent Document 1.